We investigated the expression of stem cell factor (SCF) of ocular surface constitution cells including normal human conjunctival epithelial cells, Tenon's fibroblasts, corneal epithelial cells, corneal stromal cells, SV40-immortalized corneal epithelial cell line and conjunctival epithelial cell line. SCF protein was detected in supernatant of culture medium and cell lysate of all cells determined by ELISA. Tenon's fibroblasts and corneal stromal cells express larger amount of SCF protein than epithelial cells. Relatively, SCF concentration of cell lysate in proportion to culture supernatant was higher in epithelial cells than in Tenon's fibroblasts and corneal stromal cells. Although SCF mRNA of both soluble and membrane bound form was detected in normal human conjunctival epithelial cells and corneal and conjunctival epithelial cell line, only mRNA of soluble form was detected in Tenon's fibroblasts.We evaluated the effect of many cytokines on the expression of SCF. Only interleukin-4 increased the expression of SCF protein of culture supernatant of Tenon's fibroblasts and cell lysate of corneal epithelial cell line.The effect of steroids and various types of anti-allergic drugs on the expression of SCF was evaluated. We revealed that dexamethasone decrease in SCF protein accumulation in cell lysate of corneal epithelial cell line and culture supernatant of Tenon's fibroblasts. Some anti-allergic drugs such as ketotifen fumarate were also speculated to have inhibitory effect of the expression of SCF by Tenon's fibroblasts.